The double Higgs production in an extensions of the Standard Model is analyzed. Bounds on singlet admixture in 125~GeV $h$ boson from electroweak radiative corrections and data on $h$ production and decays are obtained.
Possibility of double $h$ production enhancement at 14~TeV LHC due to heavy higgs contribution is considered. The case of see-saw type II model with isospin-triplet scalars is studied as well. In the Georgi — Machacek model the double Higgs production could be much larger than in the Standard Model. The diphoton excess with invariant mass 750 GeV will be discussed as well.